The field of the invention is position transducers and their related circuitry, and particularly, circuits for producing digital position signals from resolvers.
There are two basic types of position transducers used in industrial applications; encoders and resolvers. Encoders produce digital signals which indicate the angular orientation of a shaft. Resolvers, on the other hand, produce sinusoidal signals, and circuitry is required to convert these signals to a corresponding digital number which indicates the angular orientation of the resolver's shaft. While highly accurate encoders can be manufactured at a reasonable cost, encoders are inherently less rugged than resolvers because they require a light source and other optical elements.
Resolvers employ passive windings which are inherently rugged, but which must be precisely wound and aligned if highly accurate sinusoidal waveforms are to be produced. By using large scale integrated circuits, the conversion of these signals to digital numbers can be performed accurately and at reasonable cost. Nevertheless, resolvers capable of producing accurate, high resolution position signals are precision instruments which are relatively expensive to manufacture.